The lateral ankle sprain is the most common injury in basketball players and one of the most common overall sports injuries seen in medical emergency rooms. While this injury is most common for basketball players, it often occurs in other sports which involve jumping, and running with sharp cuts. These sports include, but are not limited to, soccer, football, volleyball, cross-country running, tennis, track, lacrosse, and baseball, as well as other activities.
The most common mechanism of injury in basketball is a player jumping up and landing on an uneven surface, often another player's shoe, such that the foot is generally in plantar flexion and inverted. When the vertically loaded lateral forces exceed the everting muscles of the lower leg, the lateral ligaments tear. The anterior talofibular ligament is the most commonly injured ligament, followed by the calcaneofibular ligament and the posterior talofibular ligament.
In the other sports described above, similar vertical loading also can occur. For example, excessive force can be applied to the medial ankle, such as when a baseball player slides into another player's ankle or when a soccer player “slide tackles” another to steal the ball.
While athletic shoes have become increasingly stylish, they have not been able to reduce the incidence of lateral ankle sprains. In fact, the nature of the design of shoes with a hard sole with firm medial and lateral edges in conjunction with a soft upper portion actually contributes to, and often exacerbates, the problems of lateral instability described above. When an ankle inverts in plantar flexion, the point of landing is on the hard lateral edge of the sports shoe, especially when a vertical load is applied when landing from a jump. The relatively softer upper portion of the shoe connected to the hard lower sole bends on an acute angle. This causes apposition of the medial part of the shoe with the medial ankle and a wide gap that forms between the soft upper shoe and the lateral ankle. It is this “disconnect” that develops between the shoe and the lateral ankle that leads to a lack of support. The forces are entirely placed on the lateral ligaments (described above) which subsequently tear, as they cannot support the full weight of the body landing on them.
A number of athletic shoes have been provided to alleviate the above concerns regarding ankle and foot inversion. One such shoe is described in U.S. Pat. No. 6,775,929 B2, the disclosure of which is incorporated by reference herein in its entirety. The present invention provides a number of improvements upon such athletic shoes, as will be described in further detail below.